The fuel battery employs a stack structure obtained by laminating a lot of fuel battery cells each constituted by a membrane electrode assembly (MEA) in which a high polymer electrolyte membrane is inserted between a pair of catalyst electrode layers, and a carbon separator. In the case that they are many, the number of the fuel battery cells is some hundreds. An oxidizing gas (an oxygen) is supplied to one catalyst electrode layer from an oxidizing gas flow path formed in one surface of each of the separators, a hydrogen is supplied to the other catalyst electrode layer from a fuel gas flow path formed in the other surface of each of the separators, and an electric power is generated on the basis of an electrochemical reaction corresponding to a reverse reaction of an electrolytic process of the water, that is, a reaction of generating the water from the hydrogen and the oxygen.
FIG. 14 is a cross sectional view showing a part of the fuel battery. Reference numeral 101 denotes a high polymer electrolyte membrane, reference symbols 102A and 102K denote catalyst electrode layers in both sides thereof, and reference numeral 103 denotes a separator. The separator 103 is provided with a gasket 104 made of a rubber-like elastic material, and a seal projection 104a is close contacted with the high polymer electrolyte membrane 101, thereby preventing the hydrogen gas and the oxygen gas supplied to the catalyst electrode layers 102A and 102K from leaking to the external. It has been conventionally known that this kind of gasket 104 is adhered to the separator 103 via an adhesive agent 105 after being formed.
In this case, since the separator 103 has an operation as a collecting plate from the catalyst electrode layers 102A and 102K in addition to an operation of sealing the gas supplied to the catalyst electrode layers 102A and 102K, and the separators 103 in both sides of the high polymer electrolyte membrane 101 or the like respectively form a negative electrode and a positive electrode, it is necessary to insulate them. Accordingly, in conventional, for example, as described in Japanese Unexamined Patent Publication No. 2003-197249, Japanese Unexamined Patent Publication No. 2001-283893 and Japanese Unexamined Patent Publication No. 2002-158018, an insulating means is provided between the separators in the periphery of a power generating portion by the MEA. In other words, in the insulating means described in the Japanese Unexamined Patent Publication No. 2003-197249, the insulation between the separators is achieved by the high polymer electrolyte membrane by making an outer peripheral edge of the high polymer electrolyte membrane into the same shape and the same size as an outer peripheral edge of the separator. Further, in the case that the size of the high polymer electrolyte membrane is limited to a peripheral edge portion of a power generating region as in the structure described in the Japanese Unexamined Patent Publication No. 2001-283893 or No. 2002-158018, a sheet-like insulating layer is interposed between the separators, in an outer peripheral side of the high polymer electrolyte membrane.
However, in accordance with the structure as shown in FIG. 14, if there is a portion where the layer of the adhesive agent 105 adhering the separator 103 (or the high polymer electrolyte membrane 101) and the gasket 104 is not applied, the leakage is generated there. Accordingly, the adhesive agent 105 is applied all around the periphery. However, if a part of the adhesive agent 105 runs over from the adhesion surface of the gasket 104 as shown by reference symbol 105a and is exposed to the gas flow path in large quantities, there is a case that a battery performance is adversely affected by an elution component from the adhesive agent 105.
Further, in accordance with the structure as described in the Japanese Unexamined Patent Publication No. 2003-197249, since an area of the expensive high polymer electrolyte membrane is expanded to a portion which is not used for power generation, there is a problem that a cost is increased. In this connection, the structure described in the Japanese Unexamined Patent Publication No. 2001-283893 or No. 2002-158018 does not have the problem mentioned above, however, an independent gasket lip (a linear projection) is provided in the sheet-like insulating layer. In this case, the gasket lip is adhered to the sheet-like insulating layer by using the adhesive agent in the light of a displacement prevention and a sealing performance. Accordingly, similarly to that shown in FIG. 14, there is a risk that a part of the adhesive agent is exposed to the gas flow path or the like and a battery performance is adversely affected by the elution component from the adhesive agent. Further, there is a risk that an adhesion peeling between the insulating layer and the gasket lip is generated in use for a long period and a sealing performance is deteriorated.